cloud ready distributed lambdas - rainfocus · •enable hybrid, object-oriented / functional...

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CloudReady:

BrianOliverArchitect|JavaSpecificationLeadOracleCloudEngineeringApril2017

Email:[email protected]:@pinocchiocode

IntroductiontoDistributedLambdas


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ProgramAgenda

Lambdas

RemoteFunctionalInterfaces&Lambdas

Demonstrations!

TheChallengesandLimitations

NextSteps

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IntroductiontoLambdas

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• Enablehybrid,object-oriented/functionalprogramminginJava• Allowyoutoeffectivelytreatcode-as-data– Both asarguments andasreturnvalues

• ExtensiveenhancementstoJavalibrariestosupportthem

AdefiningnewfeatureoftheJava8Platform

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Map<String, String> rockstars = new LinkedHashMap<>();

rockstars.put(”BG", ”Brian Goetz");rockstars.put(”BO", ”Brian Oliver");rockstars.put(”CP", ”Cameron Purdy");

rockstars.forEach((k, v) -> System.out.printf("key: %s, value: %s\n", k, v));



• Closures=function+environment

AutomaticallyCaptureSurrounding“effectivelyfinal”Context=Closures!

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String cool = ”Brian”;

Map<String, String> rockstars = new LinkedHashMap<>();

rockstars.put(”BG", ”Brian Goetz");rockstars.put(”BO", ”Brian Oliver");rockstars.put(”CP", ”Cameron Purdy");

rockstars.forEach((k, v) -> System.out.printf("key: %s is cool? %s\n”, k, v.equals(cool));



• Before:

• After:

Replaceanonymous“functionalinterface”inner-classeswithlambdas

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executor.submit(new Runnable(){public void run()

{System.out.println("Hello from anonymous class!");}

});

executor.submit(() -> System.out.println("Hello from lambda!")



• RunnableInterfaceinJava8:

Anexamplefunctionalinterface

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@FunctionalInterfacepublic interface Runnable {

/*** When an object implementing interface <code>Runnable</code> is used* to create a thread, starting the thread causes the object's* <code>run</code> method to be called in that separately executing* thread.* <p>* The general contract of the method <code>run</code> is that it may* take any action whatsoever.*/

public void run();}


But…

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Cantheybedistributedandinvokedacrossdevices,machines,data-centers…cloud?



• Wecancastthemthough…

• Output*:

StandardFunctionalInterfacesandthusLambdasarenotserializable bydefaultL

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Runnable r = (Runnable & Serializable) () -> System.out.println("Hello from lambda!");

SerializedLambda[capturingClass=class JavaExamples, functionalInterfaceMethod=java/lang/Runnable.run:()V, implementation=invokeStatic JavaExamples.lambda$serialization$2feeadd5$1:()V, instantiatedMethodType=()V, numCaptured=0]



• TherearemanynewfunctionalinterfacesinJava8:– java.util.function.Function<T,R>– java.util.function.Predicate<T>– java.util.function.Supplier<T>– java.util.function.Consumer<T>– java.util.function.BiConsumer<T,U>– java.util.function.UnaryOperator<T>– java.util.function.BinaryOperator<T>–…andtheirprimitivevariants

NoneofthenewfunctionalinterfacesareSerializableL

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• Andsomeofouroldfriendsarealsofunctionalinterfaces:– java.lang.Runnable– java.util.concurrent.Callable<V>– java.util.Comparator<T>

• Perhapsallunusableinadistributedenvironment?

NoneoftheexistingfunctionalinterfacesareSerializableL

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RemoteFunctionalInterfaces

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• Eg:TheCoherenceRemoteClassdefinesserializable functionalinterfaces

ExtensionsofexistingfunctionalinterfacestosupportSerializationJ

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public class Remote{@FunctionalInterfacepublic interface Function<T, R>

extends java.util.function.Function<T, R>, Serializable {}

@FunctionalInterfacepublic interface Runnable

extends java.lang.Runnable, Serializable {}

...}


Where’stheCloud?IntroductiontoCoherence

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• InadditiontothestandardMapmethod:

• CoherenceNamedCache alsodefines:

• JavaCompilerresolvestousethe“mostspecificoverloadedmethod”…sowe’rereadytodosomedistributedlambdas!

Mostspecificmethodswin!

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V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction);

V computeIfAbsent(K key, Remote.Function<? super K, ? extends V> mappingFunction);


Demotime!

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ChallengesandLimitations

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Oh!“Serialization:Thegiftthatkeepsongiving”

BrianGoetzJavaLanguageArchitect

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Challenge:LambdaSerialization

• Developersusemultipletypesofserialization– Javaonlyprovidesone

• Lambdasneedtobestableacrossapplicationversions– Javadoesnotprovideanysuchguarantees,it’sweakatbest

• Developerswanttointroducenewlambdaswithoutrestarting– Javaexpectsthesameversionofthecapturingclasstoexisteverywhere

• Coherenceprovidesacustomandyetcompletelycompatibleremotingframeworktosolvethesechallenges

Javaprovidesthebareminimum…inadistributedenvironmentweneedalotmore

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Limitation:ClosureSerialization

• Shouldnotreferencefieldsormethodsofthecapturingclass• Shouldnotreferenceanythingthatisn’tcertaintoexistbothontheclientandontheserver• Shouldonlycapturelocalserializable variables(useastaticfactory!)

Lambdasneedtobeselfcontainedandserializable

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public static Remote.BiFunction<String, String, String> changeName(String name){return (key, value) ->

{ return name;};

}}


Limitation:ClosureSerialization

• Shouldnotnestothernon-serializable lambdas• Don’tdothis:

• Insteaddothis:

Lambdasneedtobeselfcontainedandserializable

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Map<String, String> names = rockstars.invokeAll((entry) -> entry.extract(Person::getName));

ValueExtractor<Person, String> extractor = Person::getName;

Map<String, String> names = rockstars.invokeAll((entry) -> entry.extract(extractor));


Summary

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Summary

• LambdasareadefiningfeatureofJava8• Coherence12.2.1allowsyoutouselambdas– LikestandardJava,butbothlocally&inadistributedmanner– Allowsin-placeupdatewithoutlocking/synchronization–WithexistingCoherencefeatures(likeEntryProcessors,Listeners…)– Toperformstream-basedoperations

• Coherenceaddssupportforserializationofstandardfunctionalinterfaces• Coherencehandlesdistributedstream&lambdasinadynamicway– Supportsmultipleversionsofclientsseamlesslyrunningside-by-sidewithoutrestart

DistributedLambdasRock!Imaginethepossibilities!

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NextSteps

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StartPlaying!

• https://www.oracle.com/goto/coherence• http://coherence.me

CoherenceforDevelopers!

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https://twitter.com/OracleCoherence

https://www.linkedin.com/grp/home?gid=1782166

https://blogs.oracle.com/OracleCoherence http://www.youtube.com/OracleCoherence

cloud ready distributed lambdas - rainfocus · •enable hybrid, object-oriented / functional...

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